Imidazolium-Based Poly(ionic liquid)/Ionic Liquid Ion-Gels with High Ionic Conductivity Prepared from a Curable...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Ionic liquids (ILs) are salts that are liquid at room temperature and possess unique properties.
• Ion-gel membranes combine the characteristics of ionic liquids and polymer matrices.
• Developing stable and conductive ion-gel membranes is crucial for electrochemical applications.

Purpose of the Study:

• To prepare and characterize novel ionic liquid-based ion-gel membranes.
• To evaluate the ionic conductivity of these membranes across a range of temperatures.
• To investigate the effect of free ionic liquid content on membrane performance.

Main Methods:

• Preparation of cross-linked, free-standing ion-gel membranes from a poly(IL)-based platform.
• Incorporation of various free ionic liquids, including [EMIM][TFSI], [EMIM][FSI], [C4 IMH][TFSI], and [EAN][NO3].
• Measurement of ionic conductivity at ambient and elevated temperatures (25-110 °C).

Main Results:

• Membranes exhibited low water content (<1 wt%), except for [EAN][NO3] (≈20 wt%).
• Increasing free IL content to 80 wt% resulted in ionic conductivity ≥10⁻² S cm⁻¹ at 25 °C and ≈10⁻¹ S cm⁻¹ at 110 °C.
• Ion-gels with 70 wt% protic ILs ([C4 IMH][TFSI], [EMIM][FSI]) showed conductivity of ≈10⁻³ to 10⁻² S cm⁻¹ from 25-110 °C.

Conclusions:

• The developed ionic liquid-based ion-gel membranes demonstrate promising ionic conductivity.
• High free IL content is key to achieving high conductivity at elevated temperatures.
• These materials are suitable for applications requiring efficient ion transport over a wide temperature range.